Questions tagged [integer]
For challenges involving the manipulation of integers.
20
votes
8answers
1k views
Warped chessboard
This challenge is about building a chessboard in which the square size, instead of being constant across the board, follows a certain non-decreasing sequence, as described below.
The board is defined ...
32
votes
21answers
2k views
A Note on N!
J. E. Maxfield proved following theorem (see DOI: 10.2307/2688966):
If \$A\$ is any positive integer having \$m\$ digits, there exists a positive integer \$N\$ such that the first \$m\$ digits of \$...
-2
votes
6answers
235 views
Map values to any multidimensional array [closed]
Codegolf challenge - mapping values in a multidimensional array
[
[0, 0, 0],
[0, 0, 0],
[0, 0, 0]
]
This 2D array is sick of being so false, and wants to ...
23
votes
20answers
1k views
Maximum summed subsequences with non-adjacent items
Introduction:
Inspired by these two SO questions (no doubt from the same class): print the elements in the subarray of maximum sum without adjacent elements java and Maximum sum of non adjacent ...
8
votes
6answers
1k views
Area of a 2D convex hull [closed]
You are given an array/list/vector of pairs of integers representing cartesian coordinates (x, y) of points on a 2D Euclidean plane; all coordinates are between −104 and 104, duplicates are allowed. ...
27
votes
13answers
3k views
Valid Badminton Score?
Introduction:
I saw there was only one other badminton related challenge right now. Since I play badminton myself (for the past 13 years now), I figured I'd add some badminton-related challenges. ...
26
votes
22answers
2k views
The Digit Triangles
Challenge:
Input: A positive integer \$n\$
Output:
Create a list in the range \$[1,n]\$, and join it together to a string (i.e. \$n=13\$ would be the string ...
30
votes
23answers
8k views
Could you please stop shuffling the deck and play already?
Challenge:
Input: A list of distinct positive integers within the range \$[1, \text{list-size}]\$.
Output: An integer: the amount of times the list is riffle-shuffled. For a list, this means the ...
14
votes
11answers
860 views
Source permutation
A permutation of a set \$S = \{s_1, s_2, \dotsc, s_n\}\$ is a bijective function \$\pi: S \to S\$. For example, if \$S = \{1,2,3,4\}\$ then the function \$\pi: x \mapsto 1 + (x + 1 \mod 4)\$ is a ...
11
votes
31answers
735 views
Sum integers in a string
Input
A string.
Output
The sum of all integers in the line.
Constraints
1≤Length of line≤500
Sample test Case
Input
the 5is 108 seCONd4 a
Output
...
33
votes
5answers
8k views
Historical difference between `/` and `÷` in mathematical expressions
Introduction:
Inspired by a discussion that is already going on for many years
regarding the expression \$6÷2(1+2)\$.
With the expression \$6÷2(1+2)\$, mathematicians will quickly see that ...
7
votes
7answers
528 views
Check type of an integer
You will receive an integer less than 2000000000 and bigger than -2000000000 and you have to test what type(s) of number this is out of:
...
4
votes
9answers
274 views
Floating over the integers
As you may know, the typical binary floating point numbers in a computer language are quite different than the typical integer numbers in a computer language. Floating point numbers can represent a ...
20
votes
15answers
2k views
Square Root Distance from Integers
Given a decimal number k, find the smallest integer n such that the square root of n is ...
19
votes
25answers
2k views
23
votes
3answers
1k views
The Path Of The Wildebeest
Golf a program or function which gives the \$n^{\text{th}}\$ location of the wildebeest who starts at square \$1\$ on an infinite chessboard which is numbered in an anti-clockwise square spiral, where ...
24
votes
15answers
3k views
Matrix Jigsaw Puzzles
Input:
An integer n
Two equal-sized square matrices (with their width/height being a multiple of n)
Output:
One of two ...
24
votes
38answers
2k views
Enumerate each series of identical numbers in-place
Given a list of strictly positive integers, go through each distinct number and replace all occurrences of it with successive indices (zero or one based) of a new series.
Examples
...
23
votes
18answers
2k views
Collapsing numbers
Let's define the a function on natural numbers \$n\$, written as base 10 digits \$d_k\; d_{k-1}\; \dotsc\; d_1\; d_0\$, as follows:
As long as there are equal adjacent digits \$d_i\;d_{i-1}\$, ...
22
votes
13answers
3k views
Eight coins for the fair king
This is a "counterpart" of another puzzle, Eight coins for the fair king on Puzzling.SE.
You can read the above puzzle for the background. The details about this puzzle are as follows.
A set of 8 ...
21
votes
26answers
2k views
Digital Sumorial
Given an input n, write a program or function that outputs/returns the sum of the digital sums of n for all the bases 1 to ...
25
votes
6answers
1k views
Prime containment numbers (speed edition)
This is sequence A054261
The \$n\$th prime containment number is the lowest number which contains the first \$n\$ prime numbers as substrings. For example, the number \$235\$ is the lowest number ...
21
votes
14answers
2k views
Prime containment numbers (golf edition)
This is sequence A054261.
The \$n\$th prime containment number is the lowest number which contains the first \$n\$ prime numbers as substrings. For example, the number \$235\$ is the lowest number ...
23
votes
25answers
2k views
Sort by Largest Digit(s)
Challenge:
Given a list of integer, sort descending by their single largest digit(s). The order for numbers with the same largest digit are then sorted by second largest digit, etc.
We ignore ...
17
votes
10answers
2k views
Reciprocal copycats
Let \$A\$ be a positive integer consisting of \$n\$ decimal digits \$d_1,d_2,...,d_n\$. Let \$B\$ be another positive integer.
For the purpose of this challenge, we call \$A\$ a copycat of \$B\$ if ...
24
votes
15answers
2k views
All the single eights
Given a non-empty rectangular array of integers from 0 to 9, output the amount of cells that are ...
10
votes
9answers
1k views
Through Space and Time
Introduction:
In general we usually speak of four dimensions: three space dimensions for x, y, and ...
15
votes
45answers
2k views
Print the Lost numbers
As a big fan of the Lost TV series, I always got intrigued by the sequence of numbers that repetitively appears on the episodes. These numbers are:
\$ 4, 8, 15, 16, 23, 42\$ (A104101)
Using any ...
14
votes
28answers
2k views
The inverse Collatz Conjecture
I think the Collatz Conjecture is already well-known. But what if we invert the rules?
Start with an integer n >= 1.
Repeat the following steps:
If n is even, multiply it by 3 and add 1.
If n is ...
24
votes
25answers
1k views
New Neighbour Sequence
The non-negative integers are bored of always having the same two* neighbours, so they decide to mix things up a little. However, they are also lazy and want to stay as close as possible to their ...
17
votes
19answers
2k views
The Written Digits Sequence
Here's a reasonably trivial sequence which is not in the Online Encyclopedia of Integer Sequences.
Start with an empty sequence then define each term as the number of characters required to write out,...
9
votes
24answers
946 views
Multiplicative undelta
Let us define the "multiplicative deltas" of values \$[\; a_0, \cdots a_N, \;]\$ as:
$$
[\; a_1 / a_0, \cdots, a_{i+1} / a_i, \cdots, a_N / a_{N-1} \;]
$$
The reverse operation - namely "...
14
votes
16answers
841 views
Length of a UTF-8 byte sequence
Determine the length of a UTF-8 byte sequence given its first byte. The following table shows which ranges map to each possible length:
...
15
votes
9answers
611 views
Stagger, stack, sum
Inspired by this Stack Overflow question.
The challenge
Input
An array of square matrices containing non-negative integers.
Output
A square matrix built from the input matrices as follows.
Let \$...
26
votes
18answers
3k views
Make them sum to 10,000
We've recently reached the threshold of 10,000 questions on PPCG. Hooray! Let's celebrate this with a simple challenge.
Input
Two integers \$A\$ and \$B\$, both in \$[1..9999]\$, such that \$A+B<...
-1
votes
1answer
121 views
Every positive integer can be written as the sum of 3 palindrome integers. Wha'ts the largest possible palindrome integer for each integer n? [duplicate]
Let n be a positive integer then n = a + b + c for some a, b, and c that are palindrome integers. What is the largest possible integer ...
17
votes
18answers
4k views
Longest Repeating Subsequence of a Single Digit
Challenge:
Given a positive integer, output the longest single-digit subsequence that occurs at least twice, AND has boundaries of another digit (or the start/end of the integer).
An example:
Input:...
10
votes
7answers
641 views
Whose neighbours are hostile?
Introduction
For the purposes of this challenge, we will define the neighbours of an element \$E\$ in a square matrix \$A\$ (such that \$E=A_{i,j}\$) as all the entries of \$A\$ that are immediately ...
33
votes
41answers
5k views
Half, Half Half, and, Half
Consider the following number sequence:
\$ 0, \frac{1}{2}, \frac{1}{4}, \frac{3}{4}, \frac{1}{8}, \frac{3}{8}, \frac{5}{8}, \frac{7}{8}, \frac{1}{16}, \frac{3}{16}, \frac{5}{16}, \frac{7}{16}, \...
16
votes
18answers
5k views
Simplistic Lava Lamp
Introduction:
I think everyone knows what a Lava Lamp is, but in case they do not:
(Image source)
They're basically glass tubes that contain wax in a translucent liquid. The bottom part is heated ...
21
votes
15answers
2k views
Crown hundred crownty crown
I noticed a certain game had a peculiar life counter, which instead of stopping at 999, gained a new digit – the next number was crown hundred or ...
14
votes
15answers
1k views
Missing numbers in arithmetic sum
Challenge
Giving a valid arithmetic sum with some missing numbers, output the full expression.
Example:
...
7
votes
20answers
425 views
Find the \$\left(n^2\right)^\text{th }n\$-gonal number
Given a non-negative integer, \$n\$, yield the \$(n^2)^\text{th } n\$-gonal number.
Further Detail:
The \$x\$-gonal numbers, or polygonal numbers, are also known as the two-dimensional figurate ...
12
votes
11answers
1k views
Codegolf Rainbow : Fun with Integer-Arrays
Introduction:
(Source: Wikipedia)
When we look at a rainbow it will always have the colors from top to bottom:
Red; orange; yellow; green; blue; indigo; violet
If we look at these individual rings, ...
15
votes
21answers
1k views
Fill up to duplicate ranges
Let \$L\$ be a list of positive integers with no particular ordering, and which can contain duplicates. Write a program or function which outputs a list of positive integers \$M\$ (whose ordering is ...
25
votes
15answers
2k views
Toggle some bits and get a square
Given an integer \$N>3\$, you have to find the minimum number of bits that need to be inverted in \$N\$ to turn it into a square number. You are only allowed to invert bits below the most ...
17
votes
34answers
956 views
Calculate power series result [duplicate]
Related: Calculate Power Series Coefficients
Given a positive integer \$X\$ and a max exponent (Also a positive integer too) \$N\$ calculate the result of a power series. Example:
$$X^0+X^1+X^2+\...
19
votes
8answers
764 views
Spiral neighbourhoods
If we take the natural numbers and roll them up counter clock-wise into a spiral we end up with the following infinite spiral:
...
13
votes
12answers
2k views
Small Ramsey Numbers
Background: the Ramsey number \$R(r,s)\$ gives the minimum number of vertices \$v\$ in the complete graph \$K_v\$ such that a red/blue edge coloring of \$K_v\$ has at least one red \$K_r\$ or one blue ...
17
votes
7answers
631 views
Stacked digit staircases
Given positive integers \$w\$ and \$h\$ output \$w\$ columns and \$h\$ rows of text as described below.
The first row begins with 11 0s, the second row with 10 <...
